N6177JAir Tractor AT-502B · 1995

On July 11, 2024, about 1407 central daylight time, an Air Tractor AT-502B airplane, N6177J, and an Air Tractor AT-802A airplane, N795LA, were involved in a midair collision near Bonita, Louisiana. The Air Tractor AT-502B was destroyed and the pilot was fatally injured. The Air Tractor AT-802A sustained minor damage and the pilot was not injured. Both aircraft were operated as Title 14 Code of Federal Regulations Part 137 aerial application flights.

According to recovered data and witness information, N795LA departed a company airstrip about 2 miles west of the collision location and the planned flight was to provide aerial application to a field about 12 miles east of the airstrip. N6177J departed a company airstrip about 3 miles northeast of the collision location and the planned flight was to provide aerial application to a field about 10 miles southwest of the airstrip (see figure 1).

Figure 1. Overview of the airplanes’ departure locations and flight paths.

According to the pilot of N795LA, he departed the private airstrip and was traveling east about 200 ft above ground level. About 2 miles after departure, the pilot observed N6177J about 100 ft to his left at the same altitude. The pilot of N795LA pulled back on the control stick to avoid N6177J. Shortly after, he felt an impact and heard a bang, but was able to control the airplane after the collision. The pilot circled the area, noticed N6177J had impacted the terrain, and observed a small ground fire. Due to the unknown damage to his airplane and with the airplane being loaded with chemical, the pilot decided to complete his aerial application flight. He then returned to the airstrip and landed the airplane with the tailwheel landing gear missing from the airplane.

A witness, who was the loader for N795LA and located at the company airstrip, stated that he observed N795LA take off from the airstrip and fly east, as planned. Above a distant tree line, he observed N6177J transitioning from the northeast to the southwest and then the collision between the two airplanes. He observed one airplane descend into the terrain and then saw smoke; the other airplane continued in flight. Shortly thereafter, N795LA returned to the airstrip.

According to the operators of both airplanes, neither pilot provided radio communications during flights.

N6177J was equipped with a Satloc M3 Bantam aerial guidance system and N795LA was equipped with a Satloc G4 aerial guidance system. The M3 device and the G4 data files were sent to the NTSB Vehicle Records Laboratory for download and analysis of the data.

The data revealed that N6177J departed the airstrip northeast of the accident site about 1352 and started to travel toward the southwest. N795LA departed from the airstrip west of the accident site about 1353 and started to travel toward the east. N6177J’s data ended at 1353:32 in the vicinity of the wreckage location (see figure 2). The data revealedN795LA continued to an application area to the east before returning to land on its originating airstrip about 1406.

Figure 2. Overlay of the flight paths for both airplanes and wreckage site.

Based on the relative positions of both airplanes, as N795LA was on its easterly heading, N6177J would have been at about the pilot’s11 o’clock position. Simultaneously, about 30 seconds before the collision, as N6177J was flying on the southwesterly heading, N795LA would have been about the 1 o’clock position. Just before the collision, the data from N795LA indicated it was at 175 ft altitude and about 125 miles per hour groundspeed. N795LA was in a consistent gradual climb after takeoff, and N6177J’s altitude varied between 100 and 150 ft after takeoff. N6177J’s data ended about 20 seconds before the collision (the device manufacturer indicated that if the device abruptly loses power during an accident, up to 30 seconds of data stored in a volatile buffer may be missing from the data stored on the internal card).

An examination of the AT-502B and AT-802A planforms revealed that, with the low-wing design, downward and forward visibility was most restricted about the pilot’s 9:00 (o’clock) to 9:30 and 2:30 to 3:00 positions. Upward visibility would be restricted by the cockpit window and door frames and the cockpit roof.

The sun position data at 1407 near Bonita, Louisiana, included an azimuth of 231.34° with an altitude of 73.64° above the horizon. The sky was clear at the time of the accident.

An examination of the AT-502B and AT-802A planforms revealed that, with the low-wing design, downward and forward visibility was most restricted about the pilot’s 9:00 (o’clock) to 9:30 and 2:30 to 3:00 positions. Upward visibility would be restricted by the cockpit window and door frames and the cockpit roof.

Postaccident examination of the accident site revealed N6177J was highly fragmented, and the debris came to rest in wooded terrain, on a gravel roadway, and in adjacent roadway ditches. The outboard 6-ft section of N6177J’s left wing was separated and came to rest in the wooded terrain. The separated wing structure exhibited a semi-circular impact and black rubber transfer marks, consistent with the size of N795LA’s main landing gear tire (see figure 3). N6177J’s left horizontal stabilizer, about mid-span and mid-chord, was deflected upward and exhibited a witness mark and black rubber transfer mark, consistent with the size of N795LA’s tailwheel tire.

Figure 3. N6177J’s separated outboard left wing.

The underside of N795LA’s spreader exhibited yellow paint transfer marks and shards of paint and fiberglass, consistent with N6177J’s left wing tip. N795LA’s tailwheel and fork were found in a rice field about 750 ft east of the estimated collision location.

N6177J’s 3-blade propeller assembly remained attached to the engine propeller shaft and forward compressor section. The 3 blades were bent aft, twisted in the direction of rotation, and all 3 blade tips were separated.

N6177J was equipped with standard navigation and strobe lights on the wing tips and empennage. In addition, the forward fuselage (nose) contained two pulsating LED lights. N795LA was equipped with standard navigation and strobe lights on the wing tips and empennage.

Postaccident examination of both airplanes revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation.

On August 8, 2022, the Professional Aerial Applicator’s Support System (PAASS) published a safety bulletin on avoiding mid-air collisions. The bulletin reminded pilots of the PAASS slogan, “Ferry above five (hundred) and stay alive.” The bulletin also stated that ferrying above 500 ft agl greatly increases the chances of avoiding a collision with another agricultural aircraft making an application.

According to the AT-502B airplane flight manual, with the airplane’s hopper at an estimated full capacity, sea level altitude conditions, and a temperature of about 30° C, the airplane would have a maximum climb rate of 567 ft per minute. The distance from the departure point to the accident was about 3 miles. The estimated altitude of both airplanes at the time of the collision was about 175 ft agl.

According to an autopsy report from the Morehouse Parish Coroner’s Office, Bastrop, Louisiana, the cause of death of the AT-502B pilot was multiple blunt force injuries and the manner of death was accident. The autopsy identified mild-to-moderate atherosclerotic disease of the pilot’s coronary arteries, aortic valve, and abdominal aorta.

The pilot’s postmortem toxicology results included oxybutynin and its active metabolite desethyl oxybutynin was detected in heart blood and urine, as well as diphenhydramine in heart blood and urine.

Oxybutynin is a prescription oral anticholinergic medication commonly used to treat symptoms of an overactive bladder. Oxybutynin commonly carries a warning that it may cause central nervous system side effects including sedation and confusion, and that users should not drive or operate heavy machinery until they know how the drug affects them. Desethyl oxybutynin is an active metabolite of oxybutynin.

Diphenhydramine is a sedating antihistamine medication widely available over the counter in multiple sleep aids and cold and allergy products. Diphenhydramine can cause cognitive and psychomotor slowing and drowsiness and often carries a warning about driving and operating machinery.